Chevy Impala 2001 Clunk in Front End Left Side

About 2 weeks ago every time I back my car out of the parking space and turn the wheel, I hear a loud dull pop/clunk in the front left side of the car. It usually does it once, but may do it 2 times. I brought it to a Chevy Dealer and they replaced the 2 upper motor mounts and lubricated the Intermittant Steering Shaft, so NOW it does it also if I am on an incline and in drive but at a complete stop. When I go it pops again. I can reproduce the problem/noise if I put the car in reverse and put my foot on the break and then give it gas. It pops just once.

I brought it to Sears auto and they said it was transmission spindles. I don?t know what that is but it didn?t sound remotely right.

I then brought it to a Chevy dealer, and they said it was my upper motor mounts and my Intermittent steering shaft. So $300 later I now have new upper engine mounts with new rubber, and a freshly lubed intermittent steering shaft, AND the same problem.

Any idea what is going on. I read online people talking about CV joints, boots, and drive train, transmissions, shafts, aliens. It only happens in the front left side, and I can sometimes make it happen after I park and if I aggressively rock the car front to back.

Ball joint, upper strut mount, improperly seated coil spring, or swaybar bushings and/or end link. A bad ball joint is a safety hazard, so get this checked quickly.

Could be front Sub frame bushing. I think I remember something about shims for the sub frame bushing to stop the noise.

Also having the subframe bolts re torxed to factory specs may stop the noise, but you would think the factory trained tech would have check that.

Thank you to all who replied, and gave suggestions. The Problem is fixed!! I was amazed. It turned out that the 2 small bolts that hold the motor mounts to the frame were stripped, so they never held. Chevy replaced 4 bolts, and no more problem. I wonder if the mounts needed to be replaced to begin with, or if it was the bolts all along, but with 100,000 miles it was probably a good idea anyway.
So, endless diagnostic headache turned out to be $.39 in bolts. Ugh!!

Its alway great to here the outcome.